WO2012034690A1

WO2012034690A1 - Limitation of error propagation in line-based prediction for intra coding

Info

Publication number: WO2012034690A1
Application number: PCT/EP2011/004615
Authority: WO
Inventors: Virginie Drugeon; Matthias Narroschke
Original assignee: Panasonic Corporation
Priority date: 2010-09-14
Filing date: 2011-09-14
Publication date: 2012-03-22

Abstract

The present invention relates to encoding and decoding of image and/or video data divided into a plurality of partitions in such a way that a partition is predicted without referring to already reconstructed pixels. The encoding is then performed by coding the difference between the partition and the prediction thereof. Correspondingly, decoder operates by reconstructing the coded partitions by predicting the partition without using already reconstructed/decoded data and by adding the prediction to the received differences. Predicting without reference to previously reconstructed pixels may be achieved by signaling a predetermined value which is then used as a prediction for the partition's pixels.

Description

Limitation of error propagation in line-based prediction

for intra coding

The present invention relates to a picture coding/encoding method, apparatus and a program for executing these methods in software. In particular, the present invention relates to a method for performing intra prediction without relying on the neighboring already reconstructed pixels.

BACKGROUND OF THE INVENTION

At present, the majority of standardized video coding algorithms are based on hybrid video coding. Hybrid video coding methods typically combine several different lossless and lossy compression schemes in order to achieve the desired compression gain. Hybrid video coding is also the basis for ITU-T standards (H.26x standards such as H.261 , H.263) as well as ISO/I EC standards (MPEG-X standards such as MPEG-1 , MPEG-2, and MPEG-4). The most recent and advanced video coding standard is currently the standard denoted as H.264/MPEG-4 advanced video coding (AVC) which is a result of standardization efforts by joint video team (JVT), a joint team of ITU-T and ISO/I EC MPEG groups. A new standard is currently being developed by Joint Collaborative Team on Video Coding (JCT-VC) under a name High-Efficiency Video Coding (HEVC), aiming, in particular, at improvements of efficiency regarding the high- resolution video coding.

A video signal input to an encoder is a sequence of images called frames, each frame being a two-dimensional matrix of pixels. All the above-mentioned standards based on hybrid video coding include subdividing each individual video frame into smaller blocks (units) consisting of a plurality of pixels. The size of the blocks may vary, for instance, in accordance with the content of the image. The way of coding may be typically varied on a per block basis. The largest possible size for such a block varies. For instance in HEVC, it can be 64 x 64 pixels. In H.264/MPEG-4 AVC, a macroblock (usually denoting a block of 16 x 16 pixels) was the basic image element, for which the encoding is performed, with a possibility to further divide it in smaller subblocks to which some of the coding/decoding steps were applied. In HEVC, it is the largest coding unit (LCU). However, the coding and decoding in HEVC may also be performed for smaller coding units, for instance, for blocks of 4 x 4, 8 x 8, 16 x 16 etc. Typically, the encoding steps of a hybrid video coding include a spatial and/or a temporal prediction. Accordingly, each block (unit) to be encoded is first predicted using either the blocks in its spatial neighborhood or blocks from its temporal neighborhood, i.e. from previously encoded video frames. A block of differences between the block to be encoded and its prediction, also called block of prediction residuals, is then calculated. Another encoding step is a transformation of a block of residuals from the spatial (pixel) domain into a frequency domain. The transformation aims at reducing the correlation between the samples of the input block. Further encoding step is quantization of the coefficients resulting from the transform. In this step the actual lossy (irreversible) compression takes place. Usually, the compressed transform coefficient values are further compacted (losslessly compressed) by means of an entropy coding. In addition, side information necessary for reconstruction of the encoded video signal is encoded and provided together with the encoded video signal. This is for example information about the spatial and/or temporal prediction, amount of quantization, etc.

Figure 1 is an example of a typical H.264/ PEG-4 AVC and/or HEVC video encoder 100. A subtractor 105 first determines differences e between a current block to be encoded of an input video image (input signal s) and a corresponding prediction block s, which is used as a prediction of the current block to be encoded. The prediction signal may be obtained by a temporal or by a spatial prediction 180. The type of prediction can be varied on a per frame basis or on a per block basis. Blocks and/or frames predicted using temporal prediction are called "inter"-encoded and blocks and/or frames predicted using spatial prediction are called "intra"-encoded. Prediction signal using temporal prediction is derived from the previously encoded images, which are stored in a memory. The prediction signal using spatial prediction is derived from the values of boundary pixels in the neighboring blocks, which have been previously encoded, decoded, and stored in the memory. The difference e between the input signal and the prediction signal, denoted prediction error or residual, is transformed 1 10 resulting in coefficients, which are quantized 120. Entropy encoder 190 is then applied to the quantized coefficients in order to further reduce the amount of data to be stored and/or transmitted in a lossless way. This is mainly achieved by applying a code with code words of variable length wherein the length of a code word is chosen based on the probability of its occurrence.

Within the video encoder 100, a decoding unit is incorporated for obtaining a decoded (reconstructed) video signal s'. In compliance with the encoding steps, the decoding steps include dequantization and inverse transformation 130. The so obtained prediction error signal e' differs from the original prediction error signal due to the quantization error, called also quantization noise. A reconstructed image signal s' is then obtained by adding 140 the decoded prediction error signal e' to the prediction signal s. In order to maintain the compatibility between the encoder side and the decoder side, the prediction signal s is obtained based on the encoded and subsequently decoded video signal which is known at both sides the encoder and the decoder.

Due to the quantization, quantization noise is superposed to the reconstructed video signal. Due to the block-wise coding, the superposed noise often has blocking characteristics, which result, in particular for strong quantization, in visible block boundaries in the decoded image. Such blocking artifacts have a negative effect upon human visual perception. In order to reduce these artifacts, a deblocking filter 150 is applied to every reconstructed image block. After a deblocking filter, an adaptive loop filter 160 may be applied to the image including the already deblocked signal. Whereas the deblocking filter improves the subjective quality, ALF aims at improving the pixel-wise fidelity ("objective" quality). In particular, adaptive loop filter (ALF) is used to compensate image distortion caused by the compression.

In order to be decoded, inter-encoded blocks require also storing the previously encoded and subsequently decoded portions of image(s) in the reference frame buffer 170. An inter-encoded block is predicted 180 by employing motion compensated prediction. First, a best-matching block is found for the current block within the previously encoded and decoded video frames by a motion estimator. The best-matching block then becomes a prediction signal and the relative displacement (motion) between the current block and its best match is then signalized as motion data in the form of three-component motion vectors within the side information provided together with the encoded video data.

For both, the intra- and the inter-encoding modes, the differences e between the current input signal and the prediction signal are transformed 1 10 and quantized 120, resulting in the quantized coefficients. Generally, an orthogonal transformation such as a two-dimensional discrete cosine transformation (DCT) or an integer version thereof is employed since it reduces the correlation of the natural video images efficiently. After the transformation, lower frequency components are usually more important for image quality than high frequency components so that more bits can be spent for coding the low frequency components than the high frequency components. In the entropy coder, the two-dimensional matrix of quantized coefficients is converted into a one-dimensional array. Typically, this conversion is performed by a so-called zig-zag scanning, which starts with the DC-coefficient in the upper left corner of the two- dimensional array and scans the two-dimensional array in a predetermined sequence ending with an AC coefficient in the lower right corner. As the energy is typically concentrated in the left upper part of the two-dimensional matrix of coefficients, corresponding to the lower frequencies, the zig-zag scanning results in an array where usually the last values are zero. This allows for efficient encoding using run-length codes as a part of/before the actual entropy coding. Figure 2 illustrates an example decoder 200 according to the H.264/MPEG-4 AVC or HEVC video coding standard. The encoded video signal (input signal to the decoder) first passes to entropy decoder 290, which decodes the quantized coefficients, the information elements necessary for decoding such as motion data, mode of prediction etc. The quantized coefficients are inversely scanned in order to obtain a two-dimensional matrix, which is then fed to inverse quantization and inverse transformation 230. After inverse quantization and inverse transformation 230, a decoded (quantized) prediction error signal e' is obtained, which corresponds to the differences obtained by subtracting the prediction signal from the signal input to the encoder in the case no quantization noise is introduced and no error occurred.

The prediction signal is obtained from either a temporal or a spatial prediction 280. The decoded information elements usually further include the information necessary for the prediction such as prediction type in the case of intra-prediction and motion data in the case of motion compensated prediction. The quantized prediction error signal in the spatial domain is then added with an adder 240 to the prediction signal obtained either from the motion compensated prediction or intra-frame prediction 280. The reconstructed image may be passed through a deblocking filter 250 and an adaptive loop filter 260 and the resulting decoded signal is stored in the memory 270 to be applied for temporal or spatial prediction of the following blocks/images.

Summarizing, standardized hybrid video coders, e.g. H.264/MPEG-4 AVC or HEVC, are used to code image signals of more than one color component (like YUV, YCbCr, RGB, RGBA, etc). For the purpose of prediction, the current image to be coded is divided into blocks. It is possible to use blocks of different sizes. The applied block sizes are coded and transmitted. Standardized video coders typically apply rectangular blocks with a minimum block size, e.g. of 4x4 samples.

The H.264/MPEG-4 AVC as well as the HEVC standards includes two functional layers, a Video Coding Layer (VCL) and a Network Abstraction Layer (NAL). The VCL provides the encoding functionality as briefly described above. The NAL encapsulates syntax elements into standardized units called NAL units according to their further application such as transmission over a channel or storing in storage. The syntax elements are, for instance, the encoded prediction error signal or other information necessary for the decoding of the video signal such as type of prediction, quantization parameter, motion vectors, etc. There are VCL NAL units containing the compressed video data and the related information, as well as non-VCL units encapsulating additional data such as parameter sets relating to an entire video sequence or to its parts, or a Supplemental Enhancement Information (SEI) providing additional information that can be used to improve the decoding performance. In the current H.264/AVC or HEVC intra prediction schemes, a prediction partition (such as block) that is intra coded is currently predicted using the already reconstructed neighboring pixels. This scheme offers much better compression efficiency as without prediction because the local redundancy among the pixels is exploited. Unfortunately, the current scheme is very sensitive to errors. Indeed, if one pixel is erroneously reconstructed in one intra frame, or if a group of blocks is lost and the pixels can not be reconstructed, then the rest of the image is not predicted correctly. The consequence is that the whole image is incorrectly reconstructed from the pixel where the first error occurs provided that this pixel is further used as reference for prediction. Another problem of the current scheme is the impossibility to reconstruct the intra coded blocks in parallel. Indeed, to predict one given block, the neighboring pixels have to be completely reconstructed first.

Recently, some line-based partitioning schemes for square-shaped image blocks have been proposed. For example, in contribution JCTVC-A1 14 (JCTVC meeting, Dresden, Germany, April 2010), partitions of sizes 2x8 and 8x2 for 8x8 blocks have been introduced. In JCTVC-B040 (JCTVC meeting, Dresden, Germany, July 2010), partitions of sizes 1 x16, 16x1 , 2x8 and 8x2 have been introduced for 16x16 blocks. These partition forms are called line-based partitions. Figure 3 shows examples for partitions 1 10 and 120 of a respective size 1 x16 (Figure 3A) and 2x8 (Figure 3B).

In the paper "Intra Prediction with 1 D macroblock partitioning for image and video coding" from G. Laroche, J. Jung and B. Pesquet presented at the VCIP conference in 2009, the concept is generalized and the scan order of the 1 D partitions can be changed. In particular one interesting scan order is introduced: the hierarchical scan order. Figure 4 shows an example of hierarchical scan order for 1 D partitions of size 8x1 in a 8x8 block, where the first hierarchical level containing only partition 8 is coded, followed by the second hierarchical level containing only partition 4, then the third hierarchical level that contains partitions 2 and 6 and finally the last hierarchical level that contains partitions 1 , 3, 5 and 7.

The core idea of line-based partitioning is to improve the prediction of most image pixels by reducing the distance between the pixels to predict and the already reconstructed pixels used as reference. Unfortunately, the potential for error propagation is also increased since more pixels are likely to be used as references. SUMMARY OF THE INVENTION

In view of the above problem with the prior art, the aim of the present invention is to provide an efficient approach to spatial prediction with increased robustness against errors and their propagation, as well as increased parallel processing capabilities.

This is achieved by the subject matter of the independent claims.

Advantageous embodiments of the invention are subject to the dependent claims.

It is the particular approach of the present invention to provide partitions of the image, which are predicted without reference to the already reconstructed pixels. This approach increases robustness against error propagation and improves the quality of the reconstructed image. Since the partitions may be selected as only small portions of the image, the efficiency of coding is not affected seriously.

According to an aspect of the present invention, a method is provided for encoding image data. The method comprises partitioning the image into multiple prediction partitions, each partition including a plurality of pixels, predicting a current partition without using information from already encoded and reconstructed pixels, and encoding difference between the image data of the current partition and the prediction of the current partition.

According to another aspect of the present invention, a method is provided for decoding encoded image data partitioned into a plurality of prediction partitions, comprising predicting a current partition without using information from already reconstructed pixels, extracting from encoded image data difference between the current partition and the prediction of the current partition, and reconstructing the current partition by adding the decoded difference and the prediction.

According to still another aspect of the present invention, an apparatus is provided for encoding image data, the apparatus comprising: a partitioning unit for partitioning the image into multiple prediction partitions, each partition including a plurality of pixels, a prediction unit for predicting a current partition without using information from already encoded and reconstructed pixels, and an encoder for encoding difference between the image data of the current partition and the prediction of the current partition.

According to another aspect of the present invention, an apparatus for decoding encoded image data partitioned into a plurality of prediction partitions, the apparatus comprising: a prediction unit for predicting a current partition without using information from already reconstructed pixels, a parsing unit for extracting from encoded image data difference between the current partition and the prediction of the current partition, and a decoder for reconstructing the current partition by adding the decoded difference and the prediction.

In accordance with still another aspect of the present invention, a computer program product comprising a computer readable medium storing instructions that, when executed by the processor, perform any of the above described methods.

The accompanying drawings are incorporated into and form a part of a specification to illustrate several embodiments of the present invention. These drawings together with the description serve to explain the principles of the invention. The drawings are only for the purpose of illustrating preferred and alternative examples of how the invention can be made and used and are not to be construed as limiting the invention to only the illustrated and described embodiments. Further features and advantages will become apparent from the following and more particular description of the various embodiments of the invention, as illustrated in the accompanying drawings, in which like reference numbers refer to like elements and wherein:

Figure 1 is a block diagram illustrating an example hybrid encoder to which the present invention is applicable;

Figure 2 is a block diagram illustrating an example hybrid decoder to which the present invention is applicable;

Figure 3A is a schematic drawing illustrating an example of a 1 x16 line-partition;

Figure 3B is a schematic drawing illustrating an example of a 2x8 line partition;

Figure 4 is a schematic drawing illustrating hierarchical scan of line partitions;

Figure 5 is block diagram illustrating internal functional structure of an intra prediction selection unit being a part of the prediction unit at the encoder side;

Figure 6 is a flow diagram showing an example of determining the set of allowed prediction modes;

Figure 7 is a flow diagram showing an example of partitioning and prediction mode selection;

Figure 8 is a flow diagram showing an example of determining the prediction value for the intra-refresh mode; Figure 9 is a table illustrating an example syntax applicable for signaling at the LCU level;

Figure 10A is a table illustrating an example syntax applicable for signaling at the partition level;

Figure 10B is a table illustrating an example syntax applicable for signaling at the partition level;

Figure 1 1 is a block diagram illustrating internal functional structure of an intra prediction unit being a part of the prediction unit at the decoder side;

Figure 12 is a flow diagram of an example decoder side method for prediction according to the present invention;

Figure 13 is a schematic drawing illustrating an overall configuration of a content providing system for implementing content distribution services;

Figure 14 is a schematic drawing illustrating an overall configuration of a digital broadcasting system;

Figure 15 is a block diagram illustrating an example of a configuration of a television;

Figure 16 is a block diagram illustrating an example of a configuration of an information reproducing/recording unit that reads and writes information from or on a recording medium that is an optical disk;

Figure 17 is a schematic drawing showing an example of a configuration of a recording medium that is an optical disk;

Figure 18A is a schematic drawing illustrating an example of a cellular phone;

Figure 18B is a block diagram showing an example of a configuration of the cellular phone;

Figure 19 is a schematic drawing showing a structure of multiplexed data;

Figure 20 is a drawing schematically illustrating how each of the streams is multiplexed in multiplexed data;

Figure 21 is a schematic drawing illustrating how a video stream is stored in a stream of

PES packets in more detail; Figure 22 is a schematic drawing showing a structure of TS packets and source packets in the multiplexed data;

Figure 23 is a schematic drawing showing a data structure of a PMT;

Figure 24 is a schematic drawing showing an internal structure of multiplexed data information;

Figure 25 is a schematic drawing showing an internal structure of stream attribute information;

Figure 26 is a schematic drawing showing steps for identifying video data;

Figure 27 is a schematic block diagram illustrating an example of a configuration of an integrated circuit for implementing the video coding method and the video decoding method according to each of embodiments;

Figure 28 is a schematic drawing showing a configuration for switching between driving frequencies;

Figure 29 is a schematic drawing showing steps for identifying video data and switching between driving frequencies;

Figure 30 is a schematic drawing showing an example of a look-up table in which the standards of video data are associated with the driving frequencies;

Figure 31A is a schematic drawing showing an example of a configuration for sharing a module of a signal processing unit; and

Figure 31 B is a schematic drawing showing another example of a configuration for sharing a module of a signal processing unit.

DETAILED DESCRIPTION

The present invention discloses the introduction of a new intra prediction mode that does not rely on already reconstructed neighboring pixels, therefore reducing the potential of error propagations and allowing parallel processing capabilities in intra coding. The new intra refresh mode is introduced for some predefined small partitions, such as line-based partitions, that are likely to be used often as references. The prediction for the new intra refresh mode is calculated by setting the values of all the pixels of the partition to a fixed value that is embedded into the bitstream and signaled at region level (for example largest coding unit level in the HEVC architecture, macroblock level in the H.264/AVC architecture or slice level).

As the new intra refresh mode is introduced only for some small partitions, the coding efficiency is not significantly reduced. Furthermore, updating the value for prediction at region level allows adaptation of the value in order to limit the loss in prediction efficiency, while limiting the overhead increase since the value is usable for several partitions. Thus, an intra prediction scheme is provided that is more robust as the current H.264/AVC or HEVC intra prediction schemes against error propagation in intra frames

The image coding apparatus according to an embodiment has an intra prediction mode selection unit 500 comprising a unit 510 for determination of a set of allowed modes, several prediction mode units 521 to 52n and 530 and one selection unit 540 for selection of one prediction mode. Figure 5 is a block diagram explaining a specific construction of the intra prediction mode selection unit 500 according to this embodiment of the present invention. This intra prediction mode selection includes a determination of a set of allowed modes unit. The determination of a set of allowed modes unit takes as input the partition information about the current partition, i.e. the size, the shape and/or the position of the partition to predict. Depending on the size, the shape and the position of the partition to predict in the image, a set of allowed modes is determined for this partition. The set of allowed modes typically includes all the intra prediction modes allowed by the standard (for example H.264/AVC or HEVC) for the considered partition's size and shape. Furthermore, according to the present invention, the set of allowed modes can include an additional intra prediction mode, called an intra refresh mode. The intra prediction mode selection unit 500 further includes several prediction mode units 521 -52n and 530, depending on the set of allowed modes for the current partition. Each prediction mode unit performs prediction of the partition using one particular intra prediction mode. The intra prediction mode selection unit 500 typically includes one prediction mode unit for each intra prediction mode allowed for the partition. Therefore, N prediction mode units 521 -52n are present for each of the N intra prediction modes allowed by the standard for the current partition's size and shape. Furthermore, according to the present invention, an additional prediction unit 530 for the intra refresh mode can be present if the intra refresh mode was selected as a possible intra prediction mode for the current partition (as a result of determination of the allowed modes by the unit 510). The prediction for the intra refresh mode unit 530 takes as input a prediction value for intra refresh and calculates the prediction of the current partition by setting the values of all the pixels of the partition to the prediction value for intra refresh. The intra prediction mode selection unit 500 further includes a selection unit 540 to select one prediction mode among the set of allowed prediction modes for the current partition. One possibility to select a prediction mode is to calculate the rate distortion cost of the partition after reconstruction for each allowed intra prediction mode and to select the prediction mode with the lowest rate distortion cost. Another possibility is to select the mode giving the best prediction, i.e. the prediction that is the closest from the original image in term of mean square error. For the two above mentioned methods, the original image signal is needed for comparison purposes. Another possibility to select the prediction mode for the current partition is to consider the need for intra refresh and parallel processing. In that case, the intra refresh mode could be always selected if it belongs to the set of allowed modes for the current partition. Or the intra refresh mode could be selected for x% of the partitions that allow it, x being a value defined by the user.

Figure 6 is a flowchart explaining an example of the process to determine the set of allowed prediction modes for a given partition. The process takes as input the size, shape and position of the partition and gives as output the set of the allowed prediction modes for the input partition. The first step 610 of this process according to an embodiment of the present invention is to determine if the partition is a line-based partition. A line-based partition is a partition that is made of only one or two rows or columns and that has a rectangular shape. Furthermore, a line- based partition is generally one of several partitions contained in a square-shaped partition or block. Typical examples of line-based partitions as disclosed in prior art are 1 x16, 16x1 , 1 x8, 8x1 , 2x8 or 8x2 partitions. If the partition is not a line-based partition, for example if the partition is a block such as 4x4, 8x8, 16x16 or other square-shaped partitions, the set of allowed modes is the set to modes allowed for the given partition's size and shape by the standard as shown in step 650. For example, in H.264/AVC, that may be the nine intra prediction modes allowed by the standard if the partition is 4x4 or 8x8. If the partition is a 16x16 block, the set of allowed modes may be the four allowed intra prediction modes for 16x16 blocks. In HEVC, the set of allowed modes may be the 33 predefined prediction modes and an additional edge based prediction mode. If the partition is a line-based partition, the next step is to consider 620 the position of the line-based partition inside a block or square-shaped partition and to determine if the partition belongs to one of the partitions or hierarchy levels that allow the use of the intra refresh mode. For example, if line-based partitioning of 8x8, 16x16 or bigger blocks is allowed without hierarchical scan, the top-most or left-most line-based partition is encoded first and all the other line-based partitions of the block may be predicted using as references the pixels of the top-most or left-most partition. In that case, the top-most or left-most line-based partition of one block should allow the use of the intra refresh mode as shown in step 640.

To illustrate this example, let us consider a 16x16 block that is partitioned into sixteen 1 x16 line- based (row-based or column-based) partitions. If the partitions are column-partitions and all the partitions are encoded one after the other from left to right, then the left-most partition shown in Figure 3 is the first one to be encoded and the pixels of this partition are likely to be used as reference pixels for the second partition, whose pixels are likely to be used as references for the third partition, etc... Therefore, if the first partition is predicted with the intra refresh mode, the rest of the pixels in the 16x16 block can be encoded without any dependency to the pixels belonging to other blocks. Therefore, the left-most 1 x16 partition of the block should be allowed to use the intra refresh mode in addition to the other predefined intra prediction modes.

In case the scan is modified and includes hierarchical scan, the partitions belonging to the first hierarchy levels, i.e. the partitions that are encoded first, should be allowed to be predicted with the intra refresh mode. In the example of Figure 4, the first hierarchy level contains only partition 8. The second hierarchy level contains partition 4. The two partitions 8 and 4 are therefore important, because their pixels can be used as references for the other line-based partitions of the blocks. Therefore, the partitions 8 and 4 should be allowed to be predicted with the intra refresh mode. If the partition 8 of the current block and the partition 8 of the previously encoded block located above the current block (diagonally dashed row above the block in Figure 4) are encoded with the intra refresh mode, the whole 8x8 block can be predicted without any dependency to previously reconstructed pixels. Therefore, the whole block is resistant against previous errors and offers a stop to error propagation in the intra coded image.

The positions of the partitions that are allowed to use the intra refresh mode may be fixed in the standard or signaled in the bitstream. In the process of Figure 6, if the current partition belongs to the partitions or hierarchy levels that are allowed to use the intra refresh mode, the set of allowed modes for the current partition is made of the set of modes allowed by the standard and the intra refresh mode. Otherwise, only the set of modes allowed by the standard is allowed as shown in step 630.

In the following, the embodiment of the present invention is exemplified by applying it to the current HEVC architecture. The HEVC coding architecture partitions an image in square-shaped blocks in a recursive manner (steps 701 to 705). The image is first partitioned into LCUs (Largest Coding Units) of equal sizes. The size of an LCU is set by the user for a whole sequence and is typically 128x128 or 64x64. Each LCU can be further partitioned 702 into four CU (Coding Unit) with half the size of the LCU. For example, if the image is partitioned into LCU of sizes 128x128, each LCU can be partitioned into four CU of size 64x64. Each CU of size 64x64 can be further partitioned into four CU of size 32x32. Each CU of size 32x32 can be further partitioned into four CU of size 16x16, etc... The partitioning recursion stops 701 when the size of a CU is equal to the size of a SCU (Smallest Coding Unit) that is defined by the user and is typically equal to 4x4. The above embodiment of the present invention gives an example to introduce the intra refresh mode at the LCU level, but generally it is possible to replace the LCU level by the slice level or region level made of several CU of arbitrary sizes in the following description. In addition to the partitioning in CU, the current HEVC architecture allows prediction partitions. Each CU is predicted, the residual of the CU is calculated and transformed, the transformed coefficients are quantized and entropy coded. However, the CU can be further partitioned for prediction purposes. The partitioning of the CU into prediction units (PU) allows predicting different parts of a CU with different prediction modes. For example, to encode a CU of size NxN in inter coding, it is possible to partition the CU in two PU of sizes Nx(N/2) that are predicted using two different motion vectors. For intra coding, the partitioning schemes allowed are NxN (i.e. the whole CU is predicted with one mode), four PU of sizes (N/2)x(N/2) (i.e. four different prediction modes) or line-based partitioning schemes as described above.

Figure 7 is an exemplary flowchart to explain the process for prediction mode selection for an encoder according to the first embodiment of the present invention. The flowchart in Figure 7 is an example based on the HEVC coding architecture. The input to the process is one coding unit with a given size. The output of the process is a selected recursive partitioning (steps 701 to 705) scheme for the current CU, for each partition a selected prediction partitioning scheme 790, and for each prediction partition, a selected prediction mode 770. A standard process for residual calculation, transformation, quantization and reconstruction for each CU of the LCU runs in parallel to this process in order to provide the necessary reconstructed pixels for prediction, mode selection and partitioning selection. As such a process is not modified by the present invention, it is not illustrated and described here.

The process of Figure 7 contains two parallel processes to enable the recursive partitioning in CU. The first process on the left of Figure 7 is the recursive process. The first step 701 consists in determining if the current CU can be further partitioned, i.e. if the size of the current CU is equal to the size of the SCU or not. If a deeper partitioning is allowed, the current CU of size NxN is divided 702 into four CU of size (N/2)x(N/2). For each of the four CUs 703, the process of Figure 5 calls itself 704. When all the four CUs have been processed 705, a best partitioning scheme is selected 710 using, for example, a rate distortion analysis.

The second process on the right of Figure 7 is the process to select a prediction partitioning and accordingly, the prediction modes for the whole CU (i.e. the case when the CU of size NxN is not further partitioned into four CU). For all allowed partitioning schemes 720 in PU (for example, NxN, (N/2)x(N/2) or line-based partitioning) and for each PU 730, the process to determine the set of allowed prediction modes (process from FIG. 4) is called 800. If 740 the intra refresh mode is allowed for the current partition or PU, the prediction using the intra refresh mode is calculated 750. At this stage, the prediction value for intra refresh is not necessarily fixed. Therefore, the prediction can be performed using an initial value. Preferably, the initial value could be the latest value used, or a predefined value. For example, if bit_depth is the bit depth of the image pixels, typically 8, and if bitjncrement is the value of the internal bit depth increase, for example 4, then the initial value for intra refresh prediction may be equal to (1 «(bit_depth+bit_increment))»1 =(1 «12)»1 =2048. If bitjncrement is equal to 0, the initial value for intra refresh prediction may be equal to 128. The next step of the process in Figure 7 consists in calculating 760 the prediction for all the remaining intra prediction modes. Then, one prediction mode is selected 770 using different methods as described above (rate-distortion cost, mean square error of the prediction, necessity for intra refresh, etc). For simplicity reasons, the example in Figure 7 considers only the intra prediction case. However, inter prediction modes could be tested at this stage. When all the PU 775 and the partitioning schemes for prediction 780 have been analyzed, one partitioning scheme is selected 790. The next step is to select one partitioning depth 710. At this stage, the choice is made between a CU of size NxN with the selected prediction partitioning scheme and prediction modes or four CU of size (N/2)x(N/2).

Figure 8 is a flowchart to illustrate a process 800 to determine the intra refresh prediction value at the LCU level. The input to the process is an LCU. The output of the process is the encoded LCU with the selected recursive partitioning in CU, for each CU the selected prediction partitioning in PU, for each PU the selected prediction mode, and for the whole LCU the information if intra refresh is used and the corresponding intra refresh prediction value.

The first step 700 of the process of Figure 8 consists in calling the partitioning and prediction mode selection process as exemplified in Figure 7 for the whole LCU. After calling the process of Figure 7, the LCU is recursively partitioned in CU, each CU being partitioned in PU, each PU being predicted with a prediction mode. The next step 810 consists in determining if at least one CU is partitioned into line-based partitions for prediction purposes and if at least one of the line- based partitions is predicted with the intra refresh mode. If yes, a prediction value for the intra refresh mode is determined 820. One possibility for the prediction value is to take the DC value of the whole LCU. Another possibility is to take the average of the DC values of the partitions using the intra refresh mode in the current LCU. Another possibility is to take a predefined value calculated for the current image or being equal to the middle of the range of pixel values as previously explained. The next step 830 consists in encoding the whole LCU with the selected partitioning schemes, prediction mode and intra refresh prediction value if needed.

Figure 9 is an explanatory syntax which may be introduced at LCU level in the bitstream to signal the use or not of the new intra refresh mode inside the LCU. If the new intra refresh mode is used, it is further signaled which partitions may use the intra refresh mode and the value of the prediction for intra refresh mode. In the explanatory syntax of the first embodiment of the present invention, the new intra refresh mode is introduced only if line-based partitioning for intra prediction is allowed. In that case, the line-based partitions of one square block are either scanned with a simple scan (for top to bottom or from left to right, depending on the shape of the line-based partitions) or with a hierarchical scan. If the hierarchical scan is not allowed, the first part of the table of Figure 9 is used (marked with "no hierarchical scan"). In that case, the intra refresh mode may be allowed preferably only for the first line-based partition of one block, i.e. for the left-most or top-most partition depending on the shape of the line-based partition. A variation may consist in allowing the intra refresh mode for all line-based partitions. In that case, as showed in Figure 9, the first bit signals the use or not of the intra refresh mode inside the whole LCU. If the intra refresh mode is not used at all (the intra refresh mode was not selected for any line-based partition of the LCU allowed to be predicted with it), the bit 0 signals that the intra refresh mode is not used at all for the whole LCU. Therefore, the intra refresh mode need not be considered for any PU when writing the intra prediction mode information into the bitstream. Otherwise, the bit 1 signals that the intra refresh mode may be used. If the bit 1 is in the bitstream, the second bit signals the use of a predefined prediction value for the intra refresh mode or a further signaled prediction value. If the bit is equal to 0, a predefined prediction value is used. This value can be the middle of the range of pixel values as explained previously or one value defined for the whole image and signaled at frame level for example. This syntax may be preferred at encoder side if the intra refresh mode has been selected for only one or two partitions in the whole LCU for example. In that case, a more efficient prediction value may be less efficient in term of rate distortion because of the overhead needed to transmit the value. If the second bit is equal to 1 , the value for intra refresh prediction of all the intra refresh predicted partitions in the LCU is transmitted using the rest of the bits. In Figure 9, eight bits are used to transmit the value. However, less or more bits could be used.

If the hierarchical scan for line-based partitions is allowed, the second part of the table of Figure 9 may be used. The first bit is used to signal the use of the intra refresh mode or not in the whole LCU, same as described above for the case without hierarchical scan. The second group of bits is used to signal the hierarchical levels allowing the use of the intra refresh mode. A value 0 indicates that only the partitions belonging to the first hierarchical level may use the intra refresh mode. A value 10 indicates that the partitions belonging to the first and second hierarchical levels may use the intra refresh mode. A value 1 10 indicates that the partitions belonging to the first, second and third hierarchical levels may use the intra refresh mode, etc... A value 1 1 ...1 , containing as many ones as the number of hierarchical levels minus one, indicates that all the line-based partitions may use the intra refresh mode. The third group of bits signals with 0 or 1 that a predefined value (bit 0) or a further signaled value (bit 1 ) is used for the prediction of the intra refresh mode as explained previously for the case without hierarchical scan. If the bit is equal to 1 , the value is signaled as explained previously for the case without hierarchical scan. In case the intra refresh mode is used in the current LCU and in case the current PU is one of the partitions allowed to use the intra refresh mode, the syntax to signal the selected prediction mode must be changed at partition level in order to consider the additional intra refresh mode in the set of allowed intra modes. Figure 10 is an explanatory syntax to signal the intra prediction mode if an additional intra refresh mode is allowed for the current partition. Figure 10A is an example where the concept of most probable mode is not considered. Figure 10B is an example considering the concept of most probable mode. The concept of most probable mode for intra was introduced in H.264/AVC in order to efficiently signal the selected prediction modes for several blocks using the same mode. The prediction modes of the neighboring blocks are considered to derive a most probable mode. If the selected intra prediction mode for the current block is equal to the most probable mode only one bit is necessary to signal the use of this mode, therefore saving overhead bits in the bitstream. In the case of Figure 10A, the intra refresh mode is signaled with the bit 1 while all the other intra prediction modes are signaled with the additional bit 0 followed by an intra prediction mode codeword as defined in the standard. If a most probable mode is used, its signaling costs two bits in the syntax of Figure 0A (bit 0 to signal that it is not the intra refresh mode and bit 1 to signal the most probable mode). In that case, the intra refresh mode is not allowed to be the most probable mode. In Figure 10B, the most probable mode is signaled with bit 1 (same as in H.264/AVC). If the intra refresh mode is not the most probable mode, the intra refresh mode is signaled with the codeword 01. The other modes are signaled with the additional bits 00 followed by an intra prediction mode codeword as defined in the standard. In that case, the intra refresh mode could be potentially the most probable mode. One possibility is to set the most probable mode to the intra refresh mode when the neighboring blocks are predicted with the DC mode.

As described above, the present invention discloses the introduction of a new intra prediction mode that does not rely on already reconstructed neighboring pixels.

The new intra refresh mode provides an intra refresh point in intra coding in order to stop the possible propagation of errors. As the new intra refresh mode is introduced only for some small partitions, such as line-based partitions, the coding efficiency is not significantly reduced. Furthermore, updating the value for prediction at LCU level allows adaptation of the value in order to limit the loss in prediction efficiency, while limiting the overhead increase since the value is usable for several partitions.

In this first embodiment, the use of the intra refresh mode and the associated prediction value are signaled at LCU level. However, as already mentioned above, this level can be replaced by the slice level or an arbitrary size CU level. In the last case, all the processes described at LCU level can be used at CU level, the CU having an arbitrary size smaller as the LCU. Generally, the line-based partitions in one block use the already reconstructed pixels of the other line-based partitions of the block as references for prediction, because these pixels are often the nearest available pixels. However, some prediction modes allow the use of already reconstructed pixels belonging to other blocks. If the intra refresh mode is used for the first partition of the block, it may be useful to forbid the use of reference pixels outside the block, in order to have one block that can be predicted without any reference to other blocks. Such a block could therefore be decoded in parallel to other blocks at decoder side. To forbid the use of pixels outside the block, the prediction modes using pixels outside the block may be forbidden. Another possibility is to change the prediction modes in order to use only references inside the block. For example, for a partition of size 16x1 (horizontal row partition), the vertical mode uses only pixels from another 16x1 partition of the block located above the current partition. But the horizontal prediction uses pixels belonging to the block located to the left of the current block. The horizontal partition could be removed or changed in order to use the value of the first pixel of the 16x1 partition above. This change does not require any additional overhead information because it is applied only if the first level partition(s) of the block is (are) predicted with intra refresh.

In this first embodiment, the new intra refresh mode has been introduced for line-based partitions. The reason is that line-based partitions are relatively small partitions whose pixels are all likely to be used as references. Therefore, the impact on the coding efficiency should be limited while the impact in stopping errors propagation should be very valuable. However, the new intra refresh mode could be introduced for small square-shaped partitions as well. For example, it could be introduced for 4x4 blocks. In that case, the intra refresh mode could be allowed only for 4x4 blocks that are located at the up left corners of 8x8 blocks. The rest of the 4x4 blocks in the 8x8 blocks may use only the pixels of the upper left block or pixels derived from that block as references for prediction if the intra refresh mode is selected for the upper left block. Such 8x8 blocks would therefore be independent from the rest of the blocks.

The syntax disclosed in Figure 9 and Figure 10 is an exemplary syntax to introduce the new intra refresh mode. One other possibility for the syntax of Figure 9 using hierarchical scan would be to signal at sequence, frame or slice level, in combination with the signaling of hierarchical scan, the partitions or hierarchical levels that allow the intra refresh mode. The partitions allowing the intra refresh mode would be fixed for the whole sequence, frame or slice. The first part of Figure 9 would be used for the intra refresh mode syntax at region level instead of the second part.

Furthermore, at line-based partition level, instead of using the syntax of Figure 10, the new intra refresh mode could be signaled using the codeword of the DC mode. In that case, the new intra refresh mode would replace the DC mode for the partitions that allow the use of the intra refresh mode.

The image decoding apparatus according to a second embodiment has an intra prediction unit 1 100 containing a determination of a set of allowed modes unit 1 1 10, a determination of a prediction mode unit 1 120 and a prediction unit 1 130. Figure 1 1 is a block diagram explaining a specific construction of the intra prediction unit 1 100 of a decoder according to the second embodiment of the present invention. This intra prediction unit 1 100 has a determination of a set of allowed modes unit 1 1 10 that takes as input information about the current prediction partition, i.e. the size, the shape and the position of the partition. Depending on the size, the shape and/or the position of the partition to predict in the image, a set of allowed modes is determined for this partition using the process illustrated in Figure 6 already described above. The set of allowed modes can contain an additional intra refresh mode depending on the size, shape, position of the partition and on information signaled in the bitstream for the region or LCU containing the current partition, as described in Figure 9 for the first embodiment of the present invention (encoder). The intra prediction unit 1 100 further contains a determination of a prediction mode unit 1 120. The determination of a prediction mode unit 1 120 takes as input the codeword signaling the prediction mode for the current partition that is embedded in the bitstream and the set of allowed modes. The determination of a prediction mode unit 1 120 interprets the codeword depending on the set of allowed modes, i.e. depending on whether an additional intra refresh mode is possible for the current partition, and derives a prediction mode. The syntax of Figure 10, described above with reference to encoder side, is used to interpret the codeword. The prediction mode is given to a prediction unit 1 130 that calculates the prediction for the current partition using the signaled intra prediction mode. If the signaled intra prediction mode is the intra refresh mode, the prediction unit 1 130 needs the value for intra refresh prediction that is signaled in the bitstream using the syntax from Figure 9 and described above. If the signaled prediction mode is the intra refresh mode, the prediction of the current partition is calculated by setting the values of ail the pixels of the partition to the value for intra refresh prediction.

Figure 12 is an exemplary flowchart to explain the process for prediction for a decoder according to the second embodiment of the present invention. The process takes as input a LCU and a bitstream containing information about the intra refresh mode at LCU level and PU level, for instance as described in Figure 9 and 10. The output of the process is the prediction. A standard process for reading the residual information, inverse quantization, inverse transformation and reconstruction for each CU of the LCU runs in parallel to this process in order to provide the necessary reconstructed pixels for prediction. As such a process does not need to be modified by the present invention, it is not illustrated and described here. The first step of the process illustrated in Figure 12 is to read 1210 the bitstream at LCU level in order to determine 1215 if the intra refresh mode is used in the current LCU, for which partitions or hierarchy levels and using what value. The information may follow the syntax from Figure 9 as described in the first embodiment of the present invention. If the intra refresh mode is not used in the current LCU, the recursive information signaling the CU and PU partitioning is retrieved 1220 from the bitstream; for each 1230 prediction partition (PU) the prediction mode is read 1240 from the bitstream as described in the standard; and the partition is predicted 1250 using the signaled intra prediction mode. These steps are not necessarily modified compared to the standard such as H.264/MPEG-4 AVC or HEVC or any other standard approach. The intra prediction process is modified only if the intra refresh mode is signaled to be used in the current LCU. In that case, the recursive information signaling the CU and PU partitioning is retrieved 1270 from the bitstream. For each 1275 prediction partition or PU, the process 600 to determine the set of allowed prediction modes as described in Figure 6 is called. This process is given as input the partitions or hierarchy levels that allow the use of the intra refresh mode and that have been retrieved from the bitstream at LCU level using the syntax from Figure 9. If 1280 the intra refresh mode is not allowed for the current partition, the prediction mode is retrieved 1282 from the bitstream as described in the standard. If the intra refresh mode is allowed for the current partition, the prediction mode is retrieved 1281 from the bitstream using the syntax described in Figure 10. The next step consists in predicting 1290 the partition using the signaled intra prediction mode. If the signaled intra prediction mode is the intra refresh mode, the current partition is predicted by setting the values of all the pixels of the partition to the value for intra refresh prediction that is signaled at LCU level using the syntax from Figure 9. When all partitions have been predicted 1295, the process ends.

The new intra refresh mode provides an intra refresh point in intra coding in order to stop the possible propagation of errors and enable additional parallel processing of blocks predicted using line-based partitions.

In this second embodiment, the use of the intra refresh mode and the associated prediction value are signaled at LCU level. However, as already mentioned above, this level can be replaced by the slice level or an arbitrary size CU level.

All variations of the first embodiment described above for the encoder case can be applied to the second embodiment for the decoder case. Summarizing, the present invention provides a method for encoding image data, which divides the image data into multiple prediction partitions, each partition including a plurality of pixels. Then the method determines a prediction for a current partition without using information from already encoded and reconstructed pixels, and encodes the difference between the image data of the current partition and the prediction of the current partition.

Advantageously, the prediction is performed by predicting all the pixels of the partition with a single value that is signaled per block or a region of blocks or a region of partitions, and usable for several partitions. The value may be determined at the encoder by an optimization algorithm such as a rate-distortion optimization, since at the encoder the original image is also still available.

According to an advantageous embodiment of the present invention, only some partitions of the image are allowed to be predicted without using information from already reconstructed pixels. Other partitions and/or blocks of the image may only use other prediction methods such as spatial prediction with one of predefined prediction modes and/or temporal prediction.

The image may comprise a plurality of blocks, a block may comprise a plurality of partitions. Preferably, the positions inside a the block of the partitions that are allowed to be predicted without using information from already reconstructed pixels are signaled per block or per region including a plurality of blocks (on the region level). A region here is a block, an LCU, a slice, or any image area comprising a plurality of partitions.

The possibility to predict partitions without using information from already reconstructed pixels may be signaled at region level.

Correspondingly to the encoding, a method for decoding is provided for decoding encoded image data partitioned into a plurality of prediction partitions. The method comprises predicting a current partition without using information from already reconstructed pixels, extracting from encoded image data difference between the current partition and the prediction of the current partition, reconstructing the current partition by adding the decoded difference and the prediction.

Similarly to the encoder, the prediction is preferably performed by predicting all the pixels of the partition with a single value that is read from a bitstream at region level. Only some partitions of the image may be allowed to be predicted without using information from already reconstructed pixels and the positions inside a block of said partitions are read from a bitstream of the encoded image data at region level per block or per region including a plurality of blocks. The possibility to predict partitions without using information from already reconstructed pixels may also be read from a bitstream at region level.

A computer program product comprising a computer-readable medium having a computer- readable program code embodied thereon, the program code being adapted to carry out the method as described above is also an aspect of the present invention.

A corresponding apparatuses are also provided. In particular, an apparatus is provided for encoding image data. It comprises a partitioning unit for partitioning the image into multiple prediction partitions, each partition including a plurality of pixels, a prediction unit for predicting a current partition without using information from already encoded and reconstructed pixels, and an encoder for encoding difference between the image data of the current partition and the prediction of the current partition.

Correspondingly, an apparatus for decoding is provided for decoding the encoded image data partitioned into a plurality of prediction partitions. The apparatus comprises a prediction unit for predicting a current partition without using information from already reconstructed pixels, a parsing unit for extracting from encoded image data difference between the current partition and the prediction of the current partition, and a decoder for reconstructing the current partition by adding the decoded difference and the prediction.

The processing described in each of embodiments can be simply implemented in an independent computer system, by recording, in a recording medium, a program for implementing the configurations of the video coding method and the video decoding method described in each of embodiments. The recording media may be any recording media as long as the program can be recorded, such as a magnetic disk, an optical disk, a magnetic optical disk, an IC card, and a semiconductor memory.

Hereinafter, the applications to the video coding method and the video decoding method described in each of embodiments and systems using thereof will be described.

Figure 13 illustrates an overall configuration of a content providing system ex100 for implementing content distribution services. The area for providing communication services is divided into cells of desired size, and base stations ex106, ex107, ex108, ex109, and ex1 10 which are fixed wireless stations are placed in each of the cells.

The content providing system ex100 is connected to devices, such as a computer ex1 1 1 , a personal digital assistant (PDA) ex1 12, a camera ex1 13, a cellular phone ex1 14 and a game machine ex1 15, via the Internet ex101 , an Internet service provider ex102, a telephone network ex104, as well as the base stations ex106 to ex1 10, respectively.

However, the configuration of the content providing system ex100 is not limited to the configuration shown in Figure 13, and a combination in which any of the elements are connected is acceptable. In addition, each device may be directly connected to the telephone network ex104, rather than via the base stations ex106 to ex1 10 which are the fixed wireless stations. Furthermore, the devices may be interconnected to each other via a short distance wireless communication and others.

The camera ex1 13, such as a digital video camera, is capable of capturing video. A camera ex1 16, such as a digital video camera, is capable of capturing both still images and video. Furthermore, the cellular phone ex1 14 may be the one that meets any of the standards such as Global System for Mobile Communications (GSM), Code Division Multiple Access (CDMA), Wideband-Code Division Multiple Access (W-CDMA), Long Term Evolution (LTE), and High Speed Packet Access (HSPA). Alternatively, the cellular phone ex1 14 may be a Personal Handyphone System (PHS).

In the content providing system ex100, a streaming server ex103 is connected to the camera ex1 13 and others via the telephone network ex104 and the base station ex109, which enables distribution of images of a live show and others. In such a distribution, a content (for example, video of a music live show) captured by the user using the camera ex1 13 is coded as described above in each of embodiments, and the coded content is transmitted to the streaming server ex103. On the other hand, the streaming server ex103 carries out stream distribution of the transmitted content data to the clients upon their requests. The clients include the computer ex1 1 1 , the PDA ex1 12, the camera ex1 3, the cellular phone ex1 14, and the game machine ex1 15 that are capable of decoding the above-mentioned coded data. Each of the devices that have received the distributed data decodes and reproduces the coded data.

The captured data may be coded by the camera ex1 13 or the streaming server ex103 that transmits the data, or the coding processes may be shared between the camera ex1 13 and the streaming server ex103. Similarly, the distributed data may be decoded by the clients or the streaming server ex103, or the decoding processes may be shared between the clients and the streaming server ex103. Furthermore, the data of the still images and video captured by not only the camera ex1 13 but also the camera ex1 16 may be transmitted to the streaming server ex103 through the computer ex1 1 1 . The coding processes may be performed by the camera ex1 16, the computer ex1 1 1 , or the streaming server ex103, or shared among them. Furthermore, the coding and decoding processes may be performed by an LSI ex500 generally included in each of the computer ex1 1 1 and the devices. The LSI ex500 may be configured of a single chip or a plurality of chips. Software for coding and decoding video may be integrated into some type of a recording medium (such as a CD-ROM, a flexible disk, and a hard disk) that is readable by the computer ex1 11 and others, and the coding and decoding processes may be performed using the software. Furthermore, when the cellular phone ex1 14 is equipped with a camera, the image data obtained by the camera may be transmitted. The video data is data coded by the LSI ex500 included in the cellular phone ex1 14.

Furthermore, the streaming server ex103 may be composed of servers and computers, and may decentralize data and process the decentralized data, record, or distribute data.

As described above, the clients may receive and reproduce the coded data in the content providing system ex100. In other words, the clients can receive and decode information transmitted by the user, and reproduce the decoded data in real time in the content providing system ex100, so that the user who does not have any particular right and equipment can implement personal broadcasting.

Aside from the example of the content providing system ex100, at least one of the video coding apparatus and the video decoding apparatus described in each of embodiments may be implemented in a digital broadcasting system ex200 illustrated in Figure 14. More specifically, a broadcast station ex201 communicates or transmits, via radio waves to a broadcast satellite ex202, multiplexed data obtained by multiplexing audio data and others onto video data. The video data is data coded by the video coding method described in each of embodiments. Upon receipt of the multiplexed data, the broadcast satellite ex202 transmits radio waves for broadcasting. Then, a home-use antenna ex204 with a satellite broadcast reception function receives the radio waves.

Next, a device such as a television (receiver) ex300 and a set top box (STB) ex217 decodes the received multiplexed data, and reproduces the decoded data.

Furthermore, a reader/recorder ex218 (i) reads and decodes the multiplexed data recorded on a recording media ex215, such as a DVD and a BD, or (i) codes video signals in the recording medium ex215, and in some cases, writes data obtained by multiplexing an audio signal on the coded data. The reader/recorder ex218 can include the video decoding apparatus or the video coding apparatus as shown in each of embodiments. In this case, the reproduced video signals are displayed on the monitor ex219, and can be reproduced by another device or system using the recording medium ex215 on which the multiplexed data is recorded. It is also possible to implement the video decoding apparatus in the set top box ex217 connected to the cable ex203 for a cable television or to the antenna ex204 for satellite and/or terrestrial broadcasting, so as to display the video signals on the monitor ex219 of the television ex300. The video decoding apparatus may be implemented not in the set top box but in the television ex300.

Figure 15 illustrates the television (receiver) ex300 that uses the video coding method and the video decoding method described in each of embodiments. The television ex300 includes: a tuner ex301 that obtains or provides multiplexed data obtained by multiplexing audio data onto video data, through the antenna ex204 or the cable ex203, etc. that receives a broadcast; a modulation/demodulation unit ex302 that demodulates the received multiplexed data or modulates data into multiplexed data to be supplied outside; and a multiplexing/demultiplexing unit ex303 that demultiplexes the modulated multiplexed data into video data and audio data, or multiplexes video data and audio data coded by a signal processing unit ex306 into data.

The television ex300 further includes: a signal processing unit ex306 including an audio signal processing unit ex304 and a video signal processing unit ex305 that decode audio data and video data and code audio data and video data, respectively; and an output unit ex309 including a speaker ex307 that provides the decoded audio signal, and a display unit ex308 that displays the decoded video signal, such as a display. Furthermore, the television ex300 includes an interface unit ex317 including an operation input unit ex312 that receives an input of a user operation. Furthermore, the television ex300 includes a control unit ex310 that controls overall each constituent element of the television ex300, and a power supply circuit unit ex31 1 that supplies power to each of the elements. Other than the operation input unit ex312, the interface unit ex317 may include: a bridge ex313 that is connected to an external device, such as the reader/recorder ex218; a slot unit ex314 for enabling attachment of the recording medium ex216, such as an SD card; a driver ex315 to be connected to an external recording medium, such as a hard disk; and a modem ex316 to be connected to a telephone network. Here, the recording medium ex216 can electrically record information using a non-volatile/volatile semiconductor memory element for storage. The constituent elements of the television ex300 are connected to each other through a synchronous bus.

First, the configuration in which the television ex300 decodes multiplexed data obtained from outside through the antenna ex204 and others and reproduces the decoded data will be described. In the television ex300, upon a user operation through a remote controller ex220 and others, the multiplexing/demultiplexing unit ex303 demultiplexes the multiplexed data demodulated by the modulation/demodulation unit ex302, under control of the control unit ex310 including a CPU. Furthermore, the audio signal processing unit ex304 decodes the demultiplexed audio data, and the video signal processing unit ex305 decodes the demultiplexed video data, using the decoding method described in each of embodiments, in the television ex300. The output unit ex309 provides the decoded video signal and audio signal outside, respectively. When the output unit ex309 provides the video signal and the audio signal, the signals may be temporarily stored in buffers ex318 and ex319, and others so that the signals are reproduced in synchronization with each other. Furthermore, the television ex300 may read multiplexed data not through a broadcast and others but from the recording media ex215 and ex216, such as a magnetic disk, an optical disk, and a SD card. Next, a configuration in which the television ex300 codes an audio signal and a video signal, and transmits the data outside or writes the data on a recording medium will be described. In the television ex300, upon a user operation through the remote controller ex220 and others, the audio signal processing unit ex304 codes an audio signal, and the video signal processing unit ex305 codes a video signal, under control of the control unit ex310 using the coding method described in each of embodiments. The multiplexing/demultiplexing unit ex303 multiplexes the coded video signal and audio signal, and provides the resulting signal outside. When the multiplexing/demultiplexing unit ex303 multiplexes the video signal and the audio signal, the signals may be temporarily stored in the buffers ex320 and ex321 , and others so that the signals are reproduced in synchronization with each other. Here, the buffers ex318, ex319, ex320, and ex321 may be plural as illustrated, or at least one buffer may be shared in the television ex300. Furthermore, data may be stored in a buffer so that the system overflow and underflow may be avoided between the modulation/demodulation unit ex302 and the multiplexing/demultiplexing unit ex303, for example.

Furthermore, the television ex300 may include a configuration for receiving an AV input from a microphone or a camera other than the configuration for obtaining audio and video data from a broadcast or a recording medium, and may code the obtained data. Although the television ex300 can code, multiplex, and provide outside data in the description, it may be capable of only receiving, decoding, and providing outside data but not the coding, multiplexing, and providing outside data.

Furthermore, when the reader/recorder ex218 reads or writes multiplexed data from or on a recording medium, one of the television ex300 and the reader/recorder ex218 may decode or code the multiplexed data, and the television ex300 and the reader/recorder ex218 may share the decoding or coding.

As an example, Figure 16 illustrates a configuration of an information reproducing/recording unit ex400 when data is read or written from or on an optical disk. The information reproducing/recording unit ex400 includes constituent elements ex401 , ex402, ex403, ex404, ex405, ex406, and ex407 to be described hereinafter. The optical head ex401 irradiates a laser spot in a recording surface of the recording medium ex215 that is an optical disk to write information, and detects reflected light from the recording surface of the recording medium ex215 to read the information. The modulation recording unit ex402 electrically drives a semiconductor laser included in the optical head ex401 , and modulates the laser light according to recorded data. The reproduction demodulating unit ex403 amplifies a reproduction signal obtained by electrically detecting the reflected light from the recording surface using a photo detector included in the optical head ex401 , and demodulates the reproduction signal by separating a signal component recorded on the recording medium ex215 to reproduce the necessary information. The buffer ex404 temporarily holds the information to be recorded on the recording medium ex215 and the information reproduced from the recording medium ex215. The disk motor ex405 rotates the recording medium ex215. The servo control unit ex406 moves the optical head ex401 to a predetermined information track while controlling the rotation drive of the disk motor ex405 so as to follow the laser spot. The system control unit ex407 controls overall the information reproducing/recording unit ex400. The reading and writing processes can be implemented by the system control unit ex407 using various information stored in the buffer ex404 and generating and adding new information as necessary, and by the modulation recording unit ex402, the reproduction demodulating unit ex403, and the servo control unit ex406 that record and reproduce information through the optical head ex401 while being operated in a coordinated manner. The system control unit ex407 includes, for example, a microprocessor, and executes processing by causing a computer to execute a program for read and write.

Although the optical head ex401 irradiates a laser spot in the description, it may perform high- density recording using near field light.

Figure 17 illustrates the recording medium ex215 that is the optical disk. On the recording surface of the recording medium ex215, guide grooves are spirally formed, and an information track ex230 records, in advance, address information indicating an absolute position on the disk according to change in a shape of the guide grooves. The address information includes information for determining positions of recording blocks ex231 that are a unit for recording data. Reproducing the information track ex230 and reading the address information in an apparatus that records and reproduces data can lead to determination of the positions of the recording blocks. Furthermore, the recording medium ex215 includes a data recording area ex233, an inner circumference area ex232, and an outer circumference area ex234. The data recording area ex233 is an area for use in recording the user data. The inner circumference area ex232 and the outer circumference area ex234 that are inside and outside of the data recording area ex233, respectively are for specific use except for recording the user data. The information reproducing/recording unit 400 reads and writes coded audio, coded video data, or multiplexed data obtained by multiplexing the coded audio and video data, from and on the data recording area ex233 of the recording medium ex215. Although an optical disk having a layer, such as a DVD and a BD is described as an example in the description, the optical disk is not limited to such, and may be an optical disk having a multilayer structure and capable of being recorded on a part other than the surface. Furthermore, the optical disk may have a structure for multidimensional recording/reproduction, such as recording of information using light of colors with different wavelengths in the same portion of the optical disk and for recording information having different layers from various angles.

Furthermore, a car ex210 having an antenna ex205 can receive data from the satellite ex202 and others, and reproduce video on a display device such as a car navigation system ex21 1 set in the car ex210, in the digital broadcasting system ex200. Here, a configuration of the car navigation system ex211 will be a configuration, for example, including a GPS receiving unit from the configuration illustrated in Figure 15. The same will be true for the configuration of the computer ex1 1 1 , the cellular phone ex1 14, and others.

Figure 18A illustrates the cellular phone ex114 that uses the video coding method and the video decoding method described in embodiments. The cellular phone ex1 14 includes: an antenna ex350 for transmitting and receiving radio waves through the base station ex1 10; a camera unit ex365 capable of capturing moving and still images; and a display unit ex358 such as a liquid crystal display for displaying the data such as decoded video captured by the camera unit ex365 or received by the antenna ex350. The cellular phone ex1 14 further includes: a main body unit including an operation key unit ex366; an audio output unit ex357 such as a speaker for output of audio; an audio input unit ex356 such as a microphone for input of audio; a memory unit ex367 for storing captured video or still pictures, recorded audio, coded or decoded data of the received video, the still pictures, e-mails, or others; and a slot unit ex364 that is an interface unit for a recording medium that stores data in the same manner as the memory unit ex367.

Next, an example of a configuration of the cellular phone ex1 14 will be described with reference to Figure 18B. In the cellular phone ex1 14, a main control unit ex360 designed to control overall each unit of the main body including the display unit ex358 as well as the operation key unit ex366 is connected mutually, via a synchronous bus ex370, to a power supply circuit unit ex361 , an operation input control unit ex362, a video signal processing unit ex355, a camera interface unit ex363, a liquid crystal display (LCD) control unit ex359, a modulation/demodulation unit ex352, a multiplexing/demultiplexing unit ex353, an audio signal processing unit ex354, the slot unit ex364, and the memory unit ex367.

When a call-end key or a power key is turned ON by a user's operation, the power supply circuit unit ex361 supplies the respective units with power from a battery pack so as to activate the cell phone ex1 14. In the cellular phone ex1 14, the audio signal processing unit ex354 converts the audio signals collected by the audio input unit ex356 in voice conversation mode into digital audio signals under the control of the main control unit ex360 including a CPU, ROM, and RAM. Then, the modulation/demodulation unit ex352 performs spread spectrum processing on the digital audio signals, and the transmitting and receiving unit ex351 performs digital-to-analog conversion and frequency conversion on the data, so as to transmit the resulting data via the antenna ex350.

Also, in the cellular phone ex114, the transmitting and receiving unit ex351 amplifies the data received by the antenna ex350 in voice conversation mode and performs frequency conversion and the analog-to-digital conversion on the data. Then, the modulation/demodulation unit ex352 performs inverse spread spectrum processing on the data, and the audio signal processing unit ex354 converts it into analog audio signals, so as to output them via the audio output unit ex356.

Furthermore, when an e-mail in data communication mode is transmitted, text data of the e-mail inputted by operating the operation key unit ex366 and others of the main body is sent out to the main control unit ex360 via the operation input control unit ex362. The main control unit ex360 causes the modulation/demodulation unit ex352 to perform spread spectrum processing on the text data, and the transmitting and receiving unit ex351 performs the digital-to-analog conversion and the frequency conversion on the resulting data to transmit the data to the base station ex1 10 via the antenna ex350. When an e-mail is received, processing that is approximately inverse to the processing for transmitting an e-mail is performed on the received data, and the resulting data is provided to the display unit ex358.

When video, still images, or video and audio in data communication mode is or are transmitted, the video signal processing unit ex355 compresses and codes video signals supplied from the camera unit ex365 using the video coding method shown in each of embodiments, and transmits the coded video data to the multiplexing/demultiplexing unit ex353. In contrast, during when the camera unit ex365 captures video, still images, and others, the audio signal processing unit ex354 codes audio signals collected by the audio input unit ex356, and transmits the coded audio data to the multiplexing/demultiplexing unit ex353.

The multiplexing/demultiplexing unit ex353 multiplexes the coded video data supplied from the video signal processing unit ex355 and the coded audio data supplied from the audio signal processing unit ex354, using a predetermined method.

Then, the modulation/demodulation unit ex352 performs spread spectrum processing on the multiplexed data, and the transmitting and receiving unit ex351 performs digital-to-analog conversion and frequency conversion on the data so as to transmit the resulting data via the antenna ex350.

When receiving data of a video file which is linked to a Web page and others in data communication mode or when receiving an e-mail with video and/or audio attached, in order to decode the multiplexed data received via the antenna ex350, the multiplexing/demultiplexing unit ex353 demultiplexes the multiplexed data into a video data bit stream and an audio data bit stream, and supplies the video signal processing unit ex355 with the coded video data and the audio signal processing unit ex354 with the coded audio data, through the synchronous bus ex370. The video signal processing unit ex355 decodes the video signal using a video decoding method corresponding to the coding method shown in each of embodiments, and then the display unit ex358 displays, for instance, the video and still images included in the video file linked to the Web page via the LCD control unit ex359. Furthermore, the audio signal processing unit ex354 decodes the audio signal, and the audio output unit ex357 provides the audio.

Furthermore, similarly to the television ex300, a terminal such as the cellular phone ex1 1 probably have 3 types of implementation configurations including not only (i) a transmitting and receiving terminal including both a coding apparatus and a decoding apparatus, but also (ii) a transmitting terminal including only a coding apparatus and (iii) a receiving terminal including only a decoding apparatus. Although the digital broadcasting system ex200 receives and transmits the multiplexed data obtained by multiplexing audio data onto video data in the description, the multiplexed data may be data obtained by multiplexing not audio data but character data related to video onto video data, and may be not multiplexed data but video data itself.

As such, the video coding method and the video decoding method in each of embodiments can be used in any of the devices and systems described. Thus, the advantages described in each of embodiments can be obtained.

Furthermore, the present invention is not limited to embodiments, and various modifications and revisions are possible without departing from the scope of the present invention.

Video data can be generated by switching, as necessary, between (i) the video coding method or the video coding apparatus shown in each of embodiments and (ii) a video coding method or a video coding apparatus in conformity with a different standard, such as PEG-2, MPEG4- AVC, and VC-1 .

Here, when a plurality of video data that conforms to the different standards is generated and is then decoded, the decoding methods need to be selected to conform to the different standards. However, since to which standard each of the plurality of the video data to be decoded conform cannot be detected, there is a problem that an appropriate decoding method cannot be selected.

In order to solve the problem, multiplexed data obtained by multiplexing audio data and others onto video data has a structure including identification information indicating to which standard the video data conforms. The specific structure of the multiplexed data including the video data generated in the video coding method and by the video coding apparatus shown in each of embodiments will be hereinafter described. The multiplexed data is a digital stream in the MPEG2-Transport Stream format.

Figure 19 illustrates a structure of the multiplexed data. As illustrated in Figure 19, the multiplexed data can be obtained by multiplexing at least one of a video stream, an audio stream, a presentation graphics stream (PG), and an interactive graphics stream. The video stream represents primary video and secondary video of a movie, the audio stream (IG) represents a primary audio part and a secondary audio part to be mixed with the primary audio part, and the presentation graphics stream represents subtitles of the movie. Here, the primary video is normal video to be displayed on a screen, and the secondary video is video to be displayed on a smaller window in the primary video. Furthermore, the interactive graphics stream represents an interactive screen to be generated by arranging the GUI components on a screen. The video stream is coded in the video coding method or by the video coding apparatus shown in each of embodiments, or in a video coding method or by a video coding apparatus in conformity with a conventional standard, such as MPEG-2, MPEG4-AVC, and VC- 1 . The audio stream is coded in accordance with a standard, such as Dolby-AC-3, Dolby Digital Plus, MLP, DTS, DTS-HD, and linear PCM.

Each stream included in the multiplexed data is identified by PID. For example, 0x101 1 is allocated to the video stream to be used for video of a movie, 0x1 100 to 0x1 1 1 F are allocated to the audio streams, 0x1200 to 0x121 F are allocated to the presentation graphics streams, 0x1400 to 0x141 F are allocated to the interactive graphics streams, 0x1 B00 to 0x1 B1 F are allocated to the video streams to be used for secondary video of the movie, and 0x1 A00 to 0x1 A1 F are allocated to the audio streams to be used for the secondary video to be mixed with the primary audio.

Figure 20 schematically illustrates how data is multiplexed. First, a video stream ex235 composed of video frames and an audio stream ex238 composed of audio frames are transformed into a stream of PES packets ex236 and a stream of PES packets ex239, and further into TS packets ex237 and TS packets ex240, respectively. Similarly, data of a presentation graphics stream ex241 and data of an interactive graphics stream ex244 are transformed into a stream of PES packets ex242 and a stream of PES packets ex245, and further into TS packets ex243 and TS packets ex246, respectively. These TS packets are multiplexed into a stream to obtain multiplexed data ex247.

Figure 21 illustrates how a video stream is stored in a stream of PES packets in more detail. The first bar in Figure 21 shows a video frame stream in a video stream. The second bar shows the stream of PES packets. As indicated by arrows denoted as yy1 , yy2, yy3, and yy4 in Figure 21 , the video stream is divided into pictures as I pictures, B pictures, and P pictures each of which is a video presentation unit, and the pictures are stored in a payload of each of the PES packets. Each of the PES packets has a PES header, and the PES header stores a Presentation Time-Stamp (PTS) indicating a display time of the picture, and a Decoding Time- Stamp (DTS) indicating a decoding time of the picture.

Figure 22 illustrates a format of TS packets to be finally written on the multiplexed data. Each of the TS packets is a 188-byte fixed length packet including a 4-byte TS header having information, such as a PI D for identifying a stream and a 184-byte TS payload for storing data. The PES packets are divided, and stored in the TS payloads, respectively. When a BD ROM is used, each of the TS packets is given a 4-byte TP_Extra_Header, thus resulting in 192-byte source packets. The source packets are written on the multiplexed data. The TP_Extra_Header stores information such as an Arrival_Time_Stamp (ATS). The ATS shows a transfer start time at which each of the TS packets is to be transferred to a PID filter. The source packets are arranged in the multiplexed data as shown at the bottom of Figure 22. The numbers incrementing from the head of the multiplexed data are called source packet numbers (SPNs).

Each of the TS packets included in the multiplexed data includes not only streams of audio, video, subtitles and others, but also a Program Association Table (PAT), a Program Map Table (PMT), and a Program Clock Reference (PCR). The PAT shows what a PID in a PMT used in the multiplexed data indicates, and a PID of the PAT itself is registered as zero. The PMT stores PIDs of the streams of video, audio, subtitles and others included in the multiplexed data, and attribute information of the streams corresponding to the PIDs. The PMT also has various descriptors relating to the multiplexed data. The descriptors have information such as copy control information showing whether copying of the multiplexed data is permitted or not. The PCR stores STC time information corresponding to an ATS showing when the PCR packet is transferred to a decoder, in order to achieve synchronization between an Arrival Time Clock (ATC) that is a time axis of ATSs, and an System Time Clock (STC) that is a time axis of PTSs and DTSs. Figure 23 illustrates the data structure of the PMT in detail. A PMT header is disposed at the top of the PMT. The PMT header describes the length of data included in the PMT and others. A plurality of descriptors relating to the multiplexed data is disposed after the PMT header. Information such as the copy control information is described in the descriptors. After the descriptors, a plurality of pieces of stream information relating to the streams included in the multiplexed data is disposed. Each piece of stream information includes stream descriptors each describing information, such as a stream type for identifying a compression codec of a stream, a stream PID, and stream attribute information (such as a frame rate or an aspect ratio). The stream descriptors are equal in number to the number of streams in the multiplexed data.

When the multiplexed data is recorded on a recording medium and others, it is recorded together with multiplexed data information files.

Each of the multiplexed data information files is management information of the multiplexed data as shown in Figure 24. The multiplexed data information files are in one to one correspondence with the multiplexed data, and each of the files includes multiplexed data information, stream attribute information, and an entry map.

As illustrated in Figure 24, the multiplexed data includes a system rate, a reproduction start time, and a reproduction end time. The system rate indicates the maximum transfer rate at which a system target decoder to be described later transfers the multiplexed data to a PID filter. The intervals of the ATSs included in the multiplexed data are set to not higher than a system rate. The reproduction start time indicates a PTS in a video frame at the head of the multiplexed data. An interval of one frame is added to a PTS in a video frame at the end of the multiplexed data, and the PTS is set to the reproduction end time.

As shown in Figure 25, a piece of attribute information is registered in the stream attribute information, for each PID of each stream included in the multiplexed data. Each piece of attribute information has different information depending on whether the corresponding stream is a video stream, an audio stream, a presentation graphics stream, or an interactive graphics stream. Each piece of video stream attribute information carries information including what kind of compression codec is used for compressing the video stream, and the resolution, aspect ratio and frame rate of the pieces of picture data that is included in the video stream. Each piece of audio stream attribute information carries information including what kind of compression codec is used for compressing the audio stream, how many channels are included in the audio stream, which language the audio stream supports, and how high the sampling frequency is. The video stream attribute information and the audio stream attribute information are used for initialization of a decoder before the player plays back the information. The multiplexed data to be used is of a stream type included in the PMT. Furthermore, when the multiplexed data is recorded on a recording medium, the video stream attribute information included in the multiplexed data information is used. More specifically, the video coding method or the video coding apparatus described in each of embodiments includes a step or a unit for allocating unique information indicating video data generated by the video coding method or the video coding apparatus in each of embodiments, to the stream type included in the PMT or the video stream attribute information. With the configuration, the video data generated by the video coding method or the video coding apparatus described in each of embodiments can be distinguished from video data that conforms to another standard.

Furthermore, Figure 26 illustrates steps of the video decoding method. In Step exS100, the stream type included in the PMT or the video stream attribute information is obtained from the multiplexed data. Next, in Step exS101 , it is determined whether or not the stream type or the video stream attribute information indicates that the multiplexed data is generated by the video coding method or the video coding apparatus in each of embodiments. When it is determined that the stream type or the video stream attribute information indicates that the multiplexed data is generated by the video coding method or the video coding apparatus in each of embodiments, in Step exS102, decoding is performed by the video decoding method in each of embodiments. Furthermore, when the stream type or the video stream attribute information indicates conformance to the conventional standards, such as MPEG-2, MPEG4-AVC, and VC- 1 , in Step exS103, decoding is performed by a video decoding method in conformity with the conventional standards.

As such, allocating a new unique value to the stream type or the video stream attribute information enables determination whether or not the video decoding method or the video decoding apparatus that is described in each of embodiments can perform decoding. Even when multiplexed data that conforms to a different standard, an appropriate decoding method or apparatus can be selected. Thus, it becomes possible to decode information without any error. Furthermore, the video coding method or apparatus, or the video decoding method or apparatus can be used in the devices and systems described above.

Each of the video coding method, the video coding apparatus, the video decoding method, and the video decoding apparatus in each of embodiments is typically achieved in the form of an integrated circuit or a Large Scale Integrated (LSI) circuit. As an example of the LSI, Figure 27 illustrates a configuration of the LSI ex500 that is made into one chip. The LSI ex500 includes elements ex501 , ex502, ex503, ex504, ex505, ex506, ex507, ex508, and ex509 to be described below, and the elements are connected to each other through a bus ex510. The power supply circuit unit ex505 is activated by supplying each of the elements with power when the power supply circuit unit ex505 is turned on.

For example, when coding is performed, the LSI ex500 receives an AV signal from a microphone ex1 17, a camera ex1 13, and others through an AV IO ex509 under control of a control unit ex501 including a CPU ex502, a memory controller ex503, a stream controller ex504, and a driving frequency control unit ex512. The received AV signal is temporarily stored in an external memory ex51 1 , such as an SDRAM. Under control of the control unit ex501 , the stored data is segmented into data portions according to the processing amount and speed to be transmitted to a signal processing unit ex507. Then, the signal processing unit ex507 codes an audio signal and/or a video signal. Here, the coding of the video signal is the coding described in each of embodiments. Furthermore, the signal processing unit ex507 sometimes multiplexes the coded audio data and the coded video data, and a stream IO ex506 provides the multiplexed data outside. The provided multiplexed data is transmitted to the base station ex107, or written on the recording media ex215. When data sets are multiplexed, the data should be temporarily stored in the buffer ex508 so that the data sets are synchronized with each other.

Although the memory ex51 1 is an element outside the LSI ex500, it may be included in the LSI ex500. The buffer ex508 is not limited to one buffer, but may be composed of buffers. Furthermore, the LSI ex500 may be made into one chip or a plurality of chips.

Furthermore, although the control unit ex510 includes the CPU ex502, the memory controller ex503, the stream controller ex504, the driving frequency control unit ex512, the configuration of the control unit ex510 is not limited to such. For example, the signal processing unit ex507 may further include a CPU. Inclusion of another CPU in the signal processing unit ex507 can improve the processing speed. Furthermore, as another example, the CPU ex502 may serve as or be a part of the signal processing unit ex507, and, for example, may include an audio signal processing unit. In such a case, the control unit ex501 includes the signal processing unit ex507 or the CPU ex502 including a part of the signal processing unit ex507.

The name used here is LSI, but it may also be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

Moreover, ways to achieve integration are not limited to the LSI, and a special circuit or a general purpose processor and so forth can also achieve the integration. Field Programmable Gate Array (FPGA) that can be programmed after manufacturing LSIs or a reconfigurable processor that allows re-configuration of the connection or configuration of an LSI can be used for the same purpose. In the future, with advancement in semiconductor technology, a brand-new technology may replace LSI. The functional blocks can be integrated using such a technology. The possibility is that the present invention is applied to biotechnology.

When video data generated in the video coding method or by the video coding apparatus described in each of embodiments is decoded, compared to when video data that conforms to a conventional standard, such as MPEG-2, MPEG4-AVC, and VC-1 is decoded, the processing amount probably increases. Thus, the LSI ex500 needs to be set to a driving frequency higher than that of the CPU ex502 to be used when video data in conformity with the conventional standard is decoded. However, when the driving frequency is set higher, there is a problem that the power consumption increases.

In order to solve the problem, the video decoding apparatus, such as the television ex300 and the LSI ex500 is configured to determine to which standard the video data conforms, and switch between the driving frequencies according to the determined standard. Figure 25 illustrates a configuration ex800. A driving frequency switching unit ex803 sets a driving frequency to a higher driving frequency when video data is generated by the video coding method or the video coding apparatus described in each of embodiments. Then, the driving frequency switching unit ex803 instructs a decoding processing unit ex801 that executes the video decoding method described in each of embodiments to decode the video data. When the video data conforms to the conventional standard, the driving frequency switching unit ex803 sets a driving frequency to a lower driving frequency than that of the video data generated by the video coding method or the video coding apparatus described in each of embodiments. Then, the driving frequency switching unit ex803 instructs the decoding processing unit ex802 that conforms to the conventional standard to decode the video data.

More specifically, the driving frequency switching unit ex803 includes the CPU ex502 and the driving frequency control unit ex512 in Figure 27. Here, each of the decoding processing unit ex801 that executes the video decoding method described in each of embodiments and the decoding processing unit ex802 that conforms to the conventional standard corresponds to the signal processing unit ex507 in Figure 25. The CPU ex502 determines to which standard the video data conforms. Then, the driving frequency control unit ex512 determines a driving frequency based on a signal from the CPU ex502. Furthermore, the signal processing unit ex507 decodes the video data based on the signal from the CPU ex502. For example, the identification information described is probably used for identifying the video data. The identification information is not limited to the one described above but may be any information as long as the information indicates to which standard the video data conforms. For example, when which standard video data conforms to can be determined based on an external signal for determining that the video data is used for a television or a disk, etc., the determination may be made based on such an external signal. Furthermore, the CPU ex502 selects a driving frequency based on, for example, a look-up table in which the standards of the video data are associated with the driving frequencies as shown in Figure 30. The driving frequency can be selected by storing the look-up table in the buffer ex508 and in an internal memory of an LSI, and with reference to the look-up table by the CPU ex502.

Figure 29 illustrates steps for executing a method. First, in Step exS200, the signal processing unit ex507 obtains identification information from the multiplexed data. Next, in Step exS201 , the CPU ex502 determines whether or not the video data is generated by the coding method and the coding apparatus described in each of embodiments, based on the identification information. When the video data is generated by the video coding method and the video coding apparatus described in each of embodiments, in Step exS202, the CPU ex502 transmits a signal for setting the driving frequency to a higher driving frequency to the driving frequency control unit ex512. Then, the driving frequency control unit ex512 sets the driving frequency to the higher driving frequency. On the other hand, when the identification information indicates that the video data conforms to the conventional standard, such as MPEG-2, MPEG4-AVC, and VC-1 , in Step exS203, the CPU ex502 transmits a signal for setting the driving frequency to a lower driving frequency to the driving frequency control unit ex512. Then, the driving frequency control unit ex512 sets the driving frequency to the lower driving frequency than that in the case where the video data is generated by the video coding method and the video coding apparatus described in each of embodiment.

Furthermore, along with the switching of the driving frequencies, the power conservation effect can be improved by changing the voltage to be applied to the LSI ex500 or an apparatus including the LSI ex500. For example, when the driving frequency is set lower, the voltage to be applied to the LSI ex500 or the apparatus including the LSI ex500 is probably set to a voltage lower than that in the case where the driving frequency is set higher.

Furthermore, when the processing amount for decoding is larger, the driving frequency may be set higher, and when the processing amount for decoding is smaller, the driving frequency may be set lower as the method for setting the driving frequency. Thus, the setting method is not limited to the ones described above. For example, when the processing amount for decoding video data in conformity with MPEG 4 -AVC is larger than the processing amount for decoding video data generated by the video coding method and the video coding apparatus described in each of embodiments, the driving frequency is probably set in reverse order to the setting described above.

Furthermore, the method for setting the driving frequency is not limited to the method for setting the driving frequency lower. For example, when the identification information indicates that the video data is generated by the video coding method and the video coding apparatus described in each of embodiments, the voltage to be applied to the LSI ex500 or the apparatus including the LSI ex500 is probably set higher. When the identification information indicates that the video data conforms to the conventional standard, such as MPEG-2, MPEG4-AVC, and VC-1 , the voltage to be applied to the LSI ex500 or the apparatus including the LSI ex500 is probably set lower. As another example, when the identification information indicates that the video data is generated by the video coding method and the video coding apparatus described in each of embodiments, the driving of the CPU ex502 does not probably have to be suspended. When the identification information indicates that the video data conforms to the conventional standard, such as MPEG-2, MPEG4-AVC, and VC-1 , the driving of the CPU ex502 is probably suspended at a given time because the CPU ex502 has extra processing capacity. Even when the identification information indicates that the video data is generated by the video coding method and the video coding apparatus described in each of embodiments, in the case where the CPU ex502 has extra processing capacity, the driving of the CPU ex502 is probably suspended at a given time. In such a case, the suspending time is probably set shorter than that in the case where when the identification information indicates that the video data conforms to the conventional standard, such as MPEG-2, MPEG4-AVC, and VC-1.

Accordingly, the power conservation effect can be improved by switching between the driving frequencies in accordance with the standard to which the video data conforms. Furthermore, when the LSI ex500 or the apparatus including the LSI ex500 is driven using a battery, the battery life can be extended with the power conservation effect.

There are cases where a plurality of video data that conforms to different standards, is provided to the devices and systems, such as a television and a mobile phone. In order to enable decoding the plurality of video data that conforms to the different standards, the signal processing unit ex507 of the LSI ex500 needs to conform to the different standards. However, the problems of increase in the scale of the circuit of the LSI ex500 and increase in the cost arise with the individual use of the signal processing units ex507 that conform to the respective standards.

In order to solve the problem, what is conceived is a configuration in which the decoding processing unit for implementing the video decoding method described in each of embodiments and the decoding processing unit that conforms to the conventional standard, such as MPEG-2, MPEG4-AVC, and VC-1 are partly shared. Ex900 in Figure 31 A shows an example of the configuration. For example, the video decoding method described in each of embodiments and the video decoding method that conforms to MPEG4-AVC have, partly in common, the details of processing, such as entropy coding, inverse quantization, deblocking filtering, and motion compensated prediction. The details of processing to be shared probably includes use of a decoding processing unit ex902 that conforms to MPEG4-AVC. In contrast, a dedicated decoding processing unit ex901 is probably used for other processing unique to the present invention. Since the present invention is characterized by application of a particular spatial prediction, for example, the dedicated decoding processing unit ex901 is used for spatial prediction. Otherwise, the decoding processing unit is probably shared for one of the entropy decoding, inverse quantization, spatial or motion compensated prediction, or all of the processing. The decoding processing unit for implementing the video decoding method described in each of embodiments may be shared for the processing to be shared, and a dedicated decoding processing unit may be used for processing unique to that of MPEG4-AVC.

Furthermore, ex1000 in Figure 31 B shows another example in that processing is partly shared. This example uses a configuration including a dedicated decoding processing unit ex1001 that supports the processing unique to the present invention, a dedicated decoding processing unit ex1002 that supports the processing unique to another conventional standard, and a decoding processing unit ex1003 that supports processing to be shared between the video decoding method in the present invention and the conventional video decoding method. Here, the dedicated decoding processing units ex1001 and ex1002 are not necessarily specialized for the processing of the present invention and the processing of the conventional standard, respectively, and may be the ones capable of implementing general processing. Furthermore, the configuration can be implemented by the LSI ex500.

As such, reducing the scale of the circuit of an LSI and reducing the cost are possible by sharing the decoding processing unit for the processing to be shared between the video decoding method in the present invention and the video decoding method in conformity with the conventional standard.

Most of the examples have been outlined in relation to an H.264/AVC based video coding system, and the terminology mainly relates to the H.264/AVC terminology. However, this terminology and the description of the various embodiments with respect to H.264/AVC based coding is not intended to limit the principles and ideas of the invention to such systems. Also the detailed explanations of the encoding and decoding in compliance with the H.264/AVC standard are intended to better understand the exemplary embodiments described herein and should not be understood as limiting the invention to the described specific implementations of processes and functions in the video coding. Nevertheless, the improvements proposed herein may be readily applied in the video coding described. Furthermore the concept of the invention may be also readily used in the enhancements of H.264/AVC coding currently discussed by the JVT. Summarizing, the present invention relates to encoding and decoding of image and/or video data divided into a plurality of partitions in such a way that a partition is predicted without referring to already reconstructed pixels. The encoding is then performed by coding the difference between the partition and the prediction thereof. Correspondingly, decoder operates by reconstructing the coded partitions by predicting the partition without using already reconstructed/decoded data and by adding the prediction to the received differences. Predicting without reference to previously reconstructed pixels may be achieved by signaling a predetermined value which is then used as a prediction for the partition's pixels.

Claims

A method for encoding image data, the method comprising the steps of: partitioning the image into multiple prediction partitions, each partition including a plurality of pixels, predicting a current partition without using information from already encoded and reconstructed pixels, and encoding difference between the image data of the current partition and the prediction of the current partition.

A method according to claim 1 , wherein the prediction is performed by predicting all the pixels of the partition with a single value that is signaled at a region level and usable for several partitions.

A method according to claim 1 or 2, wherein only some partitions of the image are allowed to be predicted without using information from already reconstructed pixels.

A method according to any of claims 1 to 3, wherein the image comprises a plurality of blocks, a block comprising a plurality of partitions, and the positions inside the block of the partitions that are allowed to be predicted without using information from already reconstructed pixels are signaled per block or per region including a plurality of blocks.

A method according to any of claims 1 to 4, wherein the possibility to predict partitions without using information from already reconstructed pixels is signaled per region including a plurality of partitions.

A method for decoding encoded image data partitioned into a plurality of prediction partitions, the method comprising: predicting a current partition without using information from already reconstructed pixels, extracting from encoded image data difference between the current partition and the prediction of the current partition, and reconstructing the current partition by adding the decoded difference and the prediction.

7. A method according to claim 6, wherein the prediction is performed by predicting all the pixels of the partition with a single value that is read from a bitstream at region level.

A method according to claim 6 or 7, wherein only some partitions of the image are allowed to be predicted without using information from already reconstructed pixels and the positions inside a block of said partitions are read from a bitstream of the encoded image data per block or per region including a plurality of blocks.

9. A method according to any of claims 6 to 8, wherein the possibility to predict partitions without using information from already reconstructed pixels is read from a bitstream per region including a plurality of partitions.

10. A computer program product comprising a computer-readable medium having a computer-readable program code embodied thereon, the program code being adapted to carry out the method according to any of claims 1 to 9.

An apparatus for encoding image data, the apparatus comprising: a partitioning unit for partitioning the image into multiple prediction partitions, each partition including a plurality of pixels, a prediction unit for predicting a current partition without using information from already encoded and reconstructed pixels, and an encoder for encoding difference between the image data of the current partition and the prediction of the current partition.

12. An apparatus according to claim 1 1 , wherein the prediction unit is configured to predict all the pixels of the partition with a single value that is signaled at a region level and usable for several partitions.

An apparatus according to claim 1 1 or 12, further comprising a prediction determination unit for determining whether the current partition is allowed to be predicted without using information from already reconstructed pixels, wherein only some partitions of the image are allowed to be predicted without using information from already reconstructed pixels.

14. An apparatus according to any of claims 1 1 to 13, wherein the image comprises a plurality of blocks, a block comprising a plurality of partitions, and the positions inside the block of the partitions that are allowed to be predicted without using information from already reconstructed pixels are signaled per block or per region including a plurality of blocks.

15. An apparatus according to any of claims 1 1 to 14, further comprising an embedding unit for signaling the possibility to predict partitions without using information from already reconstructed pixels per region including a plurality of partitions.

16. An apparatus for decoding encoded image data partitioned into a plurality of prediction partitions, the apparatus comprising: a prediction unit for predicting a current partition without using information from already reconstructed pixels, a parsing unit for extracting from encoded image data difference between the current partition and the prediction of the current partition, and a decoder for reconstructing the current partition by adding the decoded difference and the prediction.

17. An apparatus according to claim 16, wherein the prediction unit is configured to predict all the pixels of the partition with a single value that is read from a bitstream at region level.

18. An apparatus according to claim 16 or 17, wherein only some partitions of the image are allowed to be predicted without using information from already reconstructed pixels and the positions inside a block of said partitions are read from a bitstream of the encoded image data per block or per region including a plurality of blocks.

19. An apparatus according to any of claims 16 to 18, further comprising an extracting unit for reading the possibility to predict partitions without using information from already reconstructed pixels from the bitstream per region including a plurality of partitions.